The present invention is directed to a device for the adjustment of the distance between a glue application roll and a web leading roll for webs of paper or of a "single-face" corrugated board located in a corrugating machine.
In the so-called "single-face" station located upstream of a corrugating machine, a first web of paper is corrugated when it is passed between two corrugating rolls, which include an upper and a lower roll. A glue applying or application roll located almost on the level of the lower corrugating roll applies glue on the crest of the corrugated paper prior to the application of a second, covering web by means of a pressure roll arranged under the lower corrugating roll.
The quality of the single-face corrugated cardboard depends very much on the quality of the glue applying operation during which a precise quantity of glue is to be applied along every paper crest. This precision regarding the quantity of glue depends on the regular and accurate thickness of the glue present on the periphery of the glue applying roll, which is part of the gluing unit. Hence, in the course of its rotation, a surface of the glue applying roll of the gluing unit will pass, first, into a glue container and then in front of a dosing roll, whole position is such that it rejects the excess or surplus glue so as to let only the required amount pass between the two rolls.
This precision regarding the quantity of glue applied depends, of course, on the accurate adjustment of the distance between the glue applying roll and the lower corrugating roll, which requires a rigorous setting of the position of the gluing unit with regard to the frame of the "single-face" station, which supports the corrugating rolls.
For the regular cleaning of the gluing unit and of the corrugating rolls, it is common to use a gluing unit which is provided with rollers to ride along rails in order to make it easy to take the gluing unit out of the device from the back of the station.
A known device for the adjustment of the distance between the glue applying roll and the lower corrugating roll comprises two conical stops which protrude at right angles from the inner surfaces of the two lateral walls of the frame of the single-face station. Each of these conical stops can be advanced into or retracted from the wall and, hence, when the gluing unit is pushed into the station until it rests on the two stops, its final position will depend on the preset advance position of each of these stops. Thus, a complete retraction of the stops provides the maximum advanced position for the unit and, hence, a minimum distance possible between the glue applying roll and the corrugating roll. However, in practice, this device has proven to be unsatisfactory because of offals or other impurities falling on the rails, which deposits involuntarily raise the unit and set the glue applying roll too close to the lower corrugating roll. Also, because of wear marks on the rails, it sometimes will provide an uncontrolled lowering of the glue applying unit, which will set the glue applying roll too far from the corrugating roll. In the first case, the crests of the corrugating paper are slightly compressed and the glue will then overflow onto either side of the crests. In the second case, the glue application is insufficient, if it even occurs.